1. Field of the Invention
The present invention relates to a substrate processing system comprising a plurality of processing parts around a transfer part for transferring substrates such as semiconductor wafers or liquid crystal glass substrates, for transferring the substrates to the processing parts through the transfer part and performing prescribed processings on the substrates.
2. Description of the Background Art
A substrate cleaning device of an individual substrate type, which is generally employed for cleaning substrates before film formation, is independent of a film forming device in general. While an improvement may be made by connecting and integrating these devices with each other, problems arising in the case of simply connecting the devices with each other are considered with reference to a virtual system shown in FIG. 8.
In this system, each of substrates W which are taken out one by one from a loader 901 is transferred by a transfer mechanism (not shown), to be cleaned in a cleaning part 902, thereafter dried in a drying part 903, then received and transferred by a transfer robot (not shown) provided on a transfer part 904, subjected to film formation in any of film forming parts 905, and thereafter transferred by the transfer part 904 again and discharged to an unloader 906. In this system, an atmosphere in the cleaning part 902 is not completely dried (hereinafter referred to as a "wet atmosphere"), while atmospheres in the drying part 903, the transfer part 904, the film forming parts 905 and the unloader 906 are completely dried (hereinafter referred to as "dry atmospheres"). With reference to a boundary area of dew points of -80.degree. C. to -5.degree. C., atmospheres having dew points of at least -5.degree. C. and not more than -80.degree. C. are referred to as wet and dry atmospheres respectively.
Processings which require the dry atmospheres cannot be performed in the wet atmosphere, and hence the device of FIG. 8 transfers the cleaned substrate W in a transfer area having an internal atmosphere gradually making transition from a wet atmosphere to a dry atmosphere, for drying the substrate W and then transferring the same to the transfer part 904.
However, the system of FIG. 8 has such disadvantages that the transfer area having the internal atmosphere gradually making transition from the wet atmosphere to the dry atmosphere is so long that the size of the system is increased, and that it is difficult to control the atmosphere in the transfer area for gradually making transition from the wet atmosphere to the dry atmosphere.